Rheological measurement of biological fluids by a portable differential dynamic microscopy-based device

Jarujareet, Ungkarn (2021) Rheological measurement of biological fluids by a portable differential dynamic microscopy-based device. PhD thesis, University of Glasgow.

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Abstract

Elementary function of fluids in being able to flow and deform continuously is an important field of study variously known as rheology. Understanding of such characteristics provides benefits for not only being able to control and understand fluid dynamics following an exposure to force. In a simple fluid, a shear stress exposed on a small fluid element causes the fluid to deform. The rate of the deformation that is proportional to the shear stress is referred to as Newtonian fluid. This rheological response reflects the intrinsic structure of the fluid from internal friction amongst the fluid. Unlike simple fluid, mechanical responses of many biological fluids are more complex due to their heterogeneity in structure. In addition, these mechanical behaviours are often relevant to the biological functionality of the fluids. For example, human whole blood exhibits a shear-thinning characteristic in which its viscosity decreases according to a progressive rate of change in velocity or shear rate. When the blood is at rest, viscosity dramatically increases due to ongoing coagulation processes to prevent and stop bleeding injuries. Several methodologies have previously been developed and demonstrated in measuring of such rheological characteristics.

This thesis exploits the emerging technique of differential dynamic microscopy (DDM) for quantitative rheological assessment of biological fluids using simple implementation of passive microrheological measurements. Improvements have been carried out to achieve and quantify reliable results. Firstly, time-stamps of every acquiring images associated more accurate dynamic (time-based) information for the typical DDM to analyse. In addition, the use of a near-infrared illumination source allowed human whole blood experiment (overcoming visible light absorbance of the blood.) Finally, the thesis implemented a direct conversion approach to eliminate high frequency artefacts of the obtained viscoelastic moduli from using generalised Stokes-Einstein relation. In order to determine the fluid viscosity the Cox-Merz relationship was adopted. Apart from rheological measurement, the developed device was successfully use to also determine particle size distribution of both colloidal particles and cells from the measurement data, applying a numerical inversion which was a non-negative least square approach.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Colleges/Schools: College of Science and Engineering > School of Engineering > Biomedical Engineering
Supervisor's Name: Cooper, Professor Jon and Reboud, Dr. Julien
Date of Award: 2021
Depositing User: Theses Team
Unique ID: glathesis:2021-82591
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 09 Dec 2021 16:20
Last Modified: 08 Apr 2022 17:09
Thesis DOI: 10.5525/gla.thesis.82591
URI: http://theses.gla.ac.uk/id/eprint/82591

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